Rotary electric machine and rotary electric machine system

ABSTRACT

In a rotary electric machine, a rotor, and a stator. The stator includes slots provided in a circumferential direction thereof, and stator windings wound in the slots. The stator windings include n groups of three-phase windings, where n is a power of 2. The slots include first slots each accommodating portions of same-group and same-phase windings in the n groups of three-phase windings. The energizing directions of the same-group and same-phase windings are identical to each other. The second slots each accommodate different-group and same-phase windings in the n groups of three-phase windings. The first slots and the second slots are arranged in the stator at predetermined intervals in a circumferential direction of the stator, and the three-phase windings of each group are wound around the stator with regular intervals therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority fromJapanese Patent Application No. 2017-077831 filed on Apr. 10, 2017, theentire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a rotary electric machine driven basedon an adjustable speed, and a rotary electric machine system includingsuch a rotary electric machine.

BACKGROUND

Conventionally, a pole-number switching rotary electric machine has beenproposed as a rotary electric machine driven based on an adjustablespeed.

SUMMARY

In a rotary electric machine, slots include first slots eachaccommodating portions of same-group and same-phase windings in the ngroups of three-phase windings. Energizing directions of the same-groupand same-phase windings are identical to each other. The slots includesecond slots each accommodating different-group and same-phase windingsin the n groups of three-phase windings. The first slots and the secondslots are arranged in the stator at predetermined intervals in acircumferential direction of the stator, and the three-phase windings ofeach group are wound around the stator with regular intervalstherebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

The object above and other objects, features and advantages of thepresent disclosure will become more apparent from the following detaileddescription with reference to the accompanying drawings. In thosedrawings:

FIG. 1 is an overall configuration diagram of a rotary electric machinesystem;

FIG. 2 is a diagram showing a configuration of a vehicle;

FIG. 3 is a cross-sectional view showing a configuration of a rotaryelectric machine;

FIG. 4 is a lateral cross-sectional view showing a configuration of eachof a rotor and a stator;

FIG. 5 is a lateral cross-sectional view showing the configuration ofeach of the rotor and the stator;

FIG. 6 is a stator winding connection diagram;

FIG. 7 is a stator winding connection diagram;

FIG. 8 is a stator winding connection diagram;

FIG. 9 is a view showing a conductor segment;

FIG. 10 is a diagram showing an energization operation in an 8-polemode,

FIG. 11 is a diagram showing an energization operation in a 4-pole mode,

FIG. 12 is a diagram showing torque characteristics in an 8-pole modeand a 4-pole mode,

FIG. 13 is a flowchart showing an energization control routine for arotary electric machine,

FIG. 14 is a transverse view showing a configuration of a rotor and astator in a second embodiment,

FIG. 15 is a stator winding connection diagram in the second embodiment,

FIG. 16 is a diagram showing an energization operation in an 8-pole modein the second embodiment,

FIG. 17 is a diagram showing an energization operation in a 4-pole modein the second embodiment,

FIG. 18 is a diagram showing a short-pitch winding configuration,

FIG. 19 is a diagram showing a long-pitch winding configuration,

FIG. 20 is a diagram showing an energization operation in a 16-pole modein a third embodiment,

FIG. 21 is a diagram showing an energization operation in a 4-pole modein the third embodiment,

FIG. 22 is a transverse view showing a configuration of a rotor and astator in a fourth embodiment,

FIG. 23 is a diagram showing an energization operation in an 8-pole modein the fourth embodiment,

FIG. 24 is a diagram showing an energization operation in a 4-pole modein the fourth embodiment,

FIG. 25 is a diagram showing a rotary electric machine system providedwith four inverters in a fifth embodiment,

FIG. 26 is a diagram showing an energization pattern in a 16-pole mode,

FIG. 27 is a diagram showing an energization pattern in a 4-pole mode,

FIG. 28 is a diagram showing an energization pattern in a 2-pole mode,

FIG. 29 is a diagram showing a rotary electric machine system providedwith eight inverters in a sixth embodiment,

FIG. 30 is a diagram showing an energization pattern in a 16-pole mode,

FIG. 31 is a diagram showing an energization pattern in an 8-pole mode,

FIG. 32 is a diagram showing an energization pattern in a 4-pole mode,

FIG. 33 is a diagram showing an energization pattern in a 2-pole mode,

FIG. 34 is an overall configuration diagram of another form of a rotaryelectric machine system,

FIG. 35 is a diagram showing another form of a rotary electric machine,

FIG. 36 is a diagram showing a magnetomotive force distribution for thepresent disclosure and for a conventional technique,

FIG. 37 is a diagram showing torque characteristics for the presentdisclosure and for a conventional technique,

FIG. 38 is a diagram showing an interlocked magnetic flux for thepresent disclosure and for the conventional technique,

FIG. 39 is a diagram showing phase voltages for the present disclosureand for the conventional technique, and

FIG. 40 is a diagram showing the torque when inverters are driven in thepresent disclosure and in the conventional technique.

DESCRIPTION OF EMBODIMENTS Viewpoint of Present Disclosure

For example, Japanese Patent Application Publication No. 2015-226425Adiscloses such a pole-number switchable induction machine. The disclosedinduction machine is configured such that a first group of distributedlywound three-phase stator windings and a second group of distributedlywound three-phase stator windings are alternately connected to first andsecond three-phase inverters every pole pair.

The first and second three-phase inverters are configured to switch afirst three-phase current flowing through the first group of three-phasestator windings and a second three-phase current flowing through thesecond group of three-phase stator windings between the same phase aseach other and the opposite phases to each other. This enables thenumber of poles of the induction machine to be changed between apredetermined number and double of the predetermined number.

Because the first group of distributedly wound three-phase statorwindings and the second group of distributedly wound three-phase statorwindings are alternately connected to the first and second three-phaseinverters every pole pair, the three-phase magnetomotive forcedistribution of the induction machine may become unbalanced while thenumber of poles of the induction machine is changed to be reduced. Thismay result in a specified phase voltage being higher, causing

(1) The high-speed operation range of the induction machine to becomelimited

(2) An increase of output torque ripple of the induction machine therebydeteriorating vibrations and noise generated from the induction machine

For addressing the above issue, the present disclosure seems to provide

(1) Rotary electric machines, each of which is designed to have a widerhigh-speed operation range

(2) A system for appropriately driving such a rotary electric machine

The following describes various aspects of the present disclosure.

A rotary electric machine according to the first aspect includes a rotorand a stator. The stator includes a plurality of slots provided in acircumferential direction thereof, and stator windings wound in theslots.

The stator windings include n groups of three-phase windings, where n isa power of 2.

The slots include first slots each accommodating portions of same-groupand same-phase windings in the n groups of three-phase windings,energizing directions of the same-group and same-phase windings beingidentical to each other. The slots include second slots eachaccommodating different-group and same-phase windings in the n groups ofthree-phase windings. The first slots and the second slots are arrangedin the stator at predetermined intervals in a circumferential directionof the stator. The three-phase windings of each group are wound aroundthe stator with regular intervals therebetween.

The first slots each accommodates portions of same-group and same-phasewindings in the n groups of three-phase windings, and energizingdirections of the same-group and same-phase windings are identical toeach other. This causes magnetomotive forces generated due toenergization of the corresponding phase windings to be added to eachother.

The second slots each accommodate different-group and same-phasewindings in the n groups of three-phase windings. This causes themagnetomotive forces between the different-group and same-phase windingsto be added to each other or cancel each other out depending on how eachof the different-group and same-phase windings is energized.

Switching the energization directions of each of the groups of phasewindings enables a first state in which the magnetomotive forces each ofthe second slots to be added to each other and a second state in whichthe magnetomotive forces are canceled each other out to be switchedtherebetween. This consequently enables the number of poles of therotary electric machine to be switched. Switching of the number of polesof the rotary electric machine results in expansion of the operatingrange of the rotary electric machine.

In particular, because the three-phase windings of each group are woundaround the stator with regular intervals therebetween, the intervalsbetween the magnetomotive forces generated by the respective phases areidentical to each other regardless of the number of poles. Consequently,torque ripples that arise due to circumferential direction imbalances inthe magnetomotive forces are reduced, and reductions in vibrations andnoise can be achieved. Furthermore, because variations in the phasevoltages can be suppressed for the same reasons, the high-speedoperating range can be further expanded.

In a rotary electric machine according to the second aspect, the firstslots respectively for different groups in the n groups are arranged atintervals of m slots in the circumferential direction of the stator, and(m−1) second slots are each arranged between a corresponding pair of thefirst slots of the different groups.

The above configuration is configured such that the first slots arearranged at intervals of m slots in the circumferential direction of thestator, and (m−1) second slots are each arranged between a correspondingpair of the first slots of the different groups. This configurationobtains an advantage of disposing the slots in which magnetomotive forceis generated, that is to say, the slots in which the energizationdirections of the two groups of phase windings are identical, with anequal spacing in the circumferential direction in each pole number modeof the rotary electric machine. As a result, the magnetomotive force canbe generated in a well-balanced fashion in the circumferentialdirection, regardless of the pole number mode.

In the rotary electric machine according to the third aspect, each ofthe second slots accommodates the same number of the different-group andsame-phase windings for each of the different groups.

This configuration enables the current amplitude to be identical foreach of the phase windings regardless of the number of poles. Becausethe voltage and current rating of the phases of the power converter canbe identical, common components can be used for the power converter, andcosts can be reduced.

This enables the voltage and current rating of each phase of a firstpower converter to be identical to that of the corresponding phase of asecond power converter, making it possible to achieve commonality ofcomponents of the first and second power converters. This results inreduction in cost of the first and second power converters.

In the rotary electric machine according to the fourth aspect, thestator windings include 2{circumflex over ( )}(A−1) groups of phasewindings as the n groups of phase windings, and the second slots includeslots, each of the slots accommodating a unique combination of twogroups of phase windings selected from the 2{circumflex over ( )}(A−1)groups of phase windings. The number of poles of the rotary electricmachine is configured to be changeable in the A steps.

In the rotary electric machine according to the fourth aspect, reversingthe energization direction of one of the phase windings of the selectedtwo groups disposed in at least one second slot against the energizationdirection of the other of the phase windings enables the number of polesof the rotary electric machine to be changeable in the A steps. Thistherefore obtains a plurality of proper torque characteristics of therotary electric machine.

In the rotary electric machine according to the fifth aspect, the ngroups of phase windings are comprised of a first group to an nth groupof phase windings, and the second slots include slots that accommodate,for each phase, (n−1) types of combinations of any two-different groupwindings selected from the first group to the nth group.

According to the fifth aspect, the two groups of phase windingsaccommodated in each of the second slots represent (n−1) types ofcombinations of any two-different group windings selected from the firstgroup to the nth group for each phase. Appropriately energizing thephase windings of each of the second slots enables changing of thenumber of poles of the rotary electric machine to be easily changed.

A rotary electric machine system according to the sixth aspect includesa rotary electric machine according to the first aspect, and acontroller that controls energization of each of the phase windings inthe rotary electric machine. The controller includes a firstenergization control unit that performs energization of each of thedifferent-phase and same-group windings accommodated in a correspondingone of the second slots such that energization directions of therespective different-phase and same-group windings are identical to eachother. The controller includes a second energization control unit thatperforms energization of each of the different-phase and same-groupwindings accommodated in a corresponding one of the second slots suchthat energization directions of the respective different-phase andsame-group windings are different from each other. The controllerincludes a switching unit that switches between energization of each ofthe different-phase and same-group windings by the first energizationcontrol unit, and energization of the each of the different-phase andsame-group windings by the second energization control unit.

Switching between energization of each of the different-phase andsame-group windings and energization of the each of the different-phaseand same-group windings makes it possible to switch between

1. The first state in which the magnetomotive forces of the phasewindings included in each first slot are added to each other and themagnetomotive forces of the phase windings included in each second slotare added to each other

2. The second state in which the magnetomotive forces of the phasewindings included in each first slot are added to each other, so thatthe magnetomotive forces of the phase windings included in each secondslot 34B are canceled each other out

As a result, it is possible to appropriately switch the number of polesaccording to a drive request and the like with respect to the rotaryelectric machine.

In a rotary electric machine system according to the seventh aspect, thesecond slots in the rotary electric machine include slots, each of theslots accommodating a unique combination of two groups of phase windingsselected from the n groups of phase windings, and the secondenergization control unit is configured to selectively perform

1. A first operation that causes energization directions of the phasewindings disposed in at least one of the second slots among all of thesecond slots to be different from each other

2. A second task that causes energization directions of the phasewindings in all of the second slots to be different from each other

This configuration enables the number of poles of the rotary electricmachine to be appropriately changed in three or more steps.

In the rotary electric machine system according to the eighth aspect,the first energization control unit is configured to perform control ofthe energization of each of the different-phase and same-group windingsaccommodated in a corresponding one of the second slots using apredetermined first number X1 of poles of the rotary electric machine.The second energization control unit is configured to, when performingcontrol of the energization of each of the different-phase andsame-group windings accommodated in a corresponding one of the secondslots using a predetermined second number X2 of poles of the rotaryelectric machine, set an energization frequency for each of thedifferent-phase and same-group windings to a value of 1/B, the secondnumber X2 being expressed by the following equation:X2=X1/B

The eighth aspect reduces the number of poles of the rotary electricmachine to the value of 1/B while reducing the energization frequencyfor each of the different-phase and same-group windings to the value of1/B. This therefore enables operations of the rotary electric machine tobe performed at a desired rotation speed even if the electrical anglephase of a power change varies due to switching from the number of polesof the rotary electric machine to another value.

The rotary electric machine system according to the ninth aspectincludes power converters provided for the respective n groups of phasewindings. The controller is configured to cause each of the powerconverters to perform power conversion to accordingly controlenergization of each of the stator windings included in a correspondingone of the second slots.

This configuration of the ninth aspect enables the power converters toparallely energize the stator windings of the respective groups, makingit possible to ensure redundancy for driving the rotary electricmachine.

Hereinafter, the following describes effects of each rotary electricmachine disclosed in the present disclosure using a conventional rotaryelectric machine, such as a variable pole number induction machine,which is different from the rotary electric machine of the presentdisclosure. Here, a pole-number switching induction machine described inJapanese Unexamined Patent Application No. 2015-226425 is assumed as theconventional rotary electric machine. That is, the pole-number switchinginduction machine is configured such that

1. A first group of distributedly wound three-phase stator windings anda second group of distributedly wound three-phase stator windings arealternately connected to first and second three-phase inverters everypole pair

2. The current phase difference between the first and second invertersis switched between an in-phase difference and a reverse phasedifference to thereby switching the number of poles of the inductionmachine with the ratio of 2:1

FIG. 36 shows the difference in magnetomotive force distribution foreach phase between the rotary electric machine of the present disclosureand the conventional rotary electric machine.

FIG. 37 shows a comparison result in torque waveform between the rotaryelectric machine of the present disclosure and the conventional rotaryelectric machine.

FIG. 38 shows a comparison result in interlinkage magnetic flux betweenthe rotary electric machine of the present disclosure and theconventional rotary electric machine.

FIG. 39 shows a comparison result in each phase voltage between therotary electric machine of the present disclosure and the conventionalrotary electric machine.

FIG. 40 shows

1. A torque comparison result, i.e. a redundancy inspection result,between the rotary electric machine of the present disclosure and theconventional rotary electric machine when each of the machines is drivenby a single inverter

2. A torque comparison result, i.e. a redundancy inspection result,between the rotary electric machine of the present disclosure and theconventional rotary electric machine when each of the machines is drivenby two inverters

In the conventional rotary electric machine, because the stator windingsare alternatingly wound every pole pair, the three-phase magnetomotiveforce distribution becomes unbalanced when the conventional rotaryelectric machine is driven in a 4-pole operation in which the number ofpoles has been reduced.

Consequently, torque ripples may become larger as shown in FIG. 37, theamplitude of the interlinkage magnetic flux may become larger as shownin FIG. 38, and/or the amplitude of each phase voltage may become largeras shown in FIG. 39. Additionally, torque ripples may become larger whenthe conventional rotary electric machine is driven by a single inverteras shown in FIG. 40.

In contrast, the rotary electric machine according to the presentdisclosure features a reduction in torque ripples, a reduction in theamplitude of the interlinkage magnetic flux, a reduction in theamplitude of each phase voltage, and/or a reduction in torque rippleswhen the rotary electric machine of the present disclosure is driven bya single inverter.

EMBODIMENTS

The following describes embodiments of the present disclosure withreference to the accompanying drawings. A rotary electric machineaccording to each embodiment is, for example, used as a power source fora vehicle. The rotary electric machine according to each embodiment canhowever be broadly used in industry, vehicles, home appliances, officeautomation (OA) equipment, game machines, and the other various devices.

In the embodiments, like parts between the embodiments, to which likereference characters are assigned, are omitted or simplified to avoidredundant description.

First Embodiment

The following describes a rotary electric machine system according tothe first embodiment of the present disclosure with reference to FIGS. 1to 13.

As shown in FIG. 1, the rotary electric machine system includes a rotaryelectric machine 10 provided with a first group of multiphase statorwindings 11 and a second group of multiphase stator windings 12.

The rotary electric machine system also includes first and secondinverters 13 and 14, a controller 15, and a power supply 16. The firstinverter 13 is connected to the first group of multiphase statorwindings 11, and the second inverter 14 is connected to the second groupof multiphase stator windings 12.

The controller 15 controls how to energize each of the first and secondinverters 13 and 14. The power supply 16 supplies power to the first andsecond inverters 13 and 14, and receives power supplied from each of thefirst and second inverters 13 and 14.

The rotary electric machine 10 is, for example, a three-phase doublewinding-type induction machine. In the present embodiment, the rotaryelectric machine 10 is a motor generator provided with a powergeneration function and a power running function, and is configured asan integrated starter generator (ISG) that serves as both an electricgenerator and an electric motor.

The first group of three-phase stator windings 11 is comprised ofU1-phase, V1-phase, and W1-phase windings, and the second group ofthree-phase stator winding 12 is comprised of U2-phase, V2-phase, andW2-phase windings. The U1- and U2-phase windings are the same U-phasewindings, the V1- and V2-phase windings are the same V-phase windings,and the W1- and W2-phase windings are the same W-phase windings.

Each of the first and second inverters 13 and 14 is, as well-known, apower conversion circuit provided with a plurality of switchingelements. Controlling switching operations of the switching elements ofthe first inverter 13 energizes the U1-phase, V1-phase, and W1-phasestator winding 11, and controlling switching operations of the switchingelements of the second inverter 14 energizes the U2-phase, V2-phase, andW2-phase stator windings 12.

The controller 15 is an electronic control device mainly comprised of amicrocomputer, and configured to perform various control task.

The controller 15 controls the first and second inverters 13 and 14 tothereby adjust a controlled variable, such as torque or rotationalspeed, of the rotary electric machine 10 to a target value based on adriving state of the vehicle, a state of charge of the power supply 16,and other parameters.

Specifically, in order to control the switching elements of each of thefirst and second inverters 13 and 14, the controller 15 obtainsmeasurement values measured by various sensors, such as a value of eachphase current measured by a current sensor 17, and a value of arotational angle of the rotary electric machine 10 measured by arotation angle sensor 18, such as a resolver.

Then, the controller 15 performs known sinusoidal PWM control based onthe measurement values measured by the various sensors to therebygenerate a binary drive signal having high and low levels for eachswitching element. Then, the controller 15 outputs the binary drivesignal to each switching element of the first inverter 13 to therebycontrol on-off switching operations of the corresponding switchingelement, and outputs the binary drive signal to each switching elementof the second inverter 14 to thereby control on-off switching operationsof the corresponding switching element.

Controlling on-off switching operations of each switching element of thefirst inverter 13 and on-off switching operations of each switchingelement of the second inverter 14 adjusts

(1) Actual currents flowing through the respective stator windings 11 torespective command current values

(2) Actual currents flowing through the respective stator windings 12 torespective command current values

FIG. 2 illustrates the configuration of a vehicle 100 to which therotary electric machine system of the present embodiment is installed.

The vehicle 100 is designed as, for example, an electric vehicle havingthe rotary electric machine 10 as its driving power source, or a hybridvehicle having the rotary electric machine 10 and an engine (not shown)as its driving power sources.

In the vehicle 100, the rotary electric machine 10 is installed in apower transmission mechanism 101 as a driving power source of thevehicle 100. The vehicle 100 includes wheels 103 and a transaxle 102such that the wheels 103 rotate together with the transaxle 102 as aresult of driving power generated by the rotary electric machine 10.

For example, each of the first and second inverters 13 and 14 isconfigured to covert direct-current (DC) power supplied from the powersupply 16 into alternating-current (AC) power. The AC power is suppliedto the rotary electric machine 10, so that the rotary electric machine10 causes the vehicle 100 to travel.

Next, the following describes the configuration of the rotary electricmachine 10 with reference to FIG. 3 and FIG. 4. In FIG. 4, illustrationof the stator windings 11 and 12 is omitted for convenience of thedescription of the machine 10.

The rotary electric machine 10 includes a rotary shaft 21, a rotor 22, astator 23, and a housing 24. The rotor 22 is mounted on the rotary shaft21, and the stator 23 is arranged to surround the rotor 22. The housing24 accommodates the rotor 22 and the stator 23 such that the rotor 22and the stator 23 are coaxially disposed to each other. The housing 24is provided with bearings 25 and 26, and the rotation shaft 21 and therotor 22 are rotatably supported by the bearings 25 and 26.

The rotor 22 has a rotor core 31, and also has a plurality of conductors32 mounted to an outer circumferential portion of the rotor core 31; theouter peripheral portion of the rotor core 31 radially faces an innercircumferential portion of the stator 23.

The rotor core 31 is comprised of a plurality of annular electromagneticsteel plates that are stacked in their axial directions and are forexample swaged to each other. The rotor 22 is configured as an inductiverotor.

The stator 23 includes an annular stator core 35 provided with aplurality of slots 34 arranged in a circumferential direction of thestator core 35. The stator 23 also includes the first group ofthree-phase stator windings 11 and the second group of three-phasestator windings 12 that are distributedly wound in the slots 34, so thatthe first group of three-phase stator windings 11 and the second groupof three-phase stator windings 12 are wound around the stator core 35 ofthe common stator 23.

As shown in FIG. 1, the U1-phase, V1-phase, and W1-phase windings of thestator winding 11 have a phase difference of 120 electrical degrees fromeach other. First ends of the U1-, V1-, and W1-phase stator windings 11are connected to a common neutral point N1. The U2-phase, V2-phase, andW2-phase windings of the stator winding 12 have a phase difference of120 electrical degrees from each other. First ends of the U2-, V2-, andW2-phase stator windings 12 are connected to a common neutral point N2.

The stator core 35 is comprised of a plurality of annularelectromagnetic steel plates that are stacked in their axial directionsand are for example swaged to each other. The stator core 35 includes anannular yoke 36 and a plurality of teeth 37. The teeth 37 are arrangedto protrude radially inward from the yoke 36 with predetermined regularintervals therebetween in the circumferential direction of the yoke 36.

The stator core 35 is also comprised of slots 34 each formed between acorresponding pair of adjacent teeth 37. As described above, the teeth37 are provided with the regular intervals therebetween in thecircumferential direction of the yoke 36.

Each of the slots 34 has an elongated opening shape in the radialdirection of the stator core 35. The number of slots 34 of the firstembodiment is set to 24, and the 24 slots 34 are formed in the yoke 36to be arranged with regular intervals in the circumferential directionof the yoke 36. Slots numbers #1 to #24 are assigned to the respective24 slots 34.

The stator windings 11 and 12 are would in corresponding slots in theslots 34 such that two portions selected from at least one of the statorwindings 11 and the stator windings 12 are disposed in the respectiveinner side and outer side of each slot 34 (see FIG. 5). In each slot 34,an insulating member is disposed to enclose individually the twoportions disposed in the corresponding slot 34.

In FIG. 5, the portions of the first group of stator windings 11 arerepresented by darker shading than the portions of the second group ofstator windings 12.

Note that the rotary electric machine 10 can be configured to include nsets of three-phase windings, where n is a power of two. The rotaryelectric machine 10 of the first embodiment is configured to include twosets of three-phase windings 11 and 12, that is, n is set to 2.

The slots 34 of the stator core 35 of the rotary electric machine 10according to the first embodiment include single-group slots 34A andmixed-group slots 34B.

In each of the single-winding slots 34A, portions of the same phasewinding in the same group are disposed; the direction of a currentflowing through one of these portions is identical to the direction of acurrent flowing through the other thereof.

In each of the mixed-winding slots 34B, portions of the same phasewindings in the respective different groups are disposed. Thesingle-group slots 34A are arranged at predetermined intervals in thecircumferential direction of the stator core 35, and the mixed-groupslots 34B are arranged at predetermined intervals in the circumferentialdirection of the stator core 35.

Each single-group slot 34A corresponds to a first slot, and amixed-group slot 34B corresponds to a second slot. The details of thesingle-phase and mixed-group slots 34A and 34B will be described below.

FIG. 6 shows the winding state of the stator windings 11 and 12 withrespect to the #1 to #24 slots 34. In FIG. 6, for example, a portion ofthe U1-phase winding is disposed in the outer side of the #1 slot 34,and another portion of the U1 phase winding is disposed in the innerside of the #1 slot 34. The inner and outer portions of the U1-phasewinding are energized in a mutually identical direction.

Additionally, a portion of the W1-phase winding is disposed in the outerside of the #2 slot, and a portion of the W2-phase winding is disposedin the inner side of the #2 slot.

That is, the #1 slot 34 serves as one of the single-group slots 34A toaccommodate portions of the same phase winding in the same group aredisposed; the direction of a current flowing through one of theseportions is identical to the direction of a current flowing through theother thereof. In contrast, the #2 slot 34 serves as one of thesame-phase slots 34 b to accommodate portions of the same phase windingsin the respective different groups.

In the same manner, the #3, #5, and #7 slots and the like (odd-numberedslots) are single-group slots 34A, and the #4, #6, and #8 slots and thelike (even-numbered slots) are mixed-group slots 34B.

In the first embodiment, the single-group slots 34A and the mixed-groupslots 34B are alternatingly arranged in the stator core 35. In otherwords, the single-group slots 34A are arranged at the prescribedintervals in the circumferential direction, and the mixed-group slots34B are each arranged between a corresponding one adjacent pair of thesingle-group slots 34A.

Here, each of the stator windings 11 and 12 is configured by joining aplurality of conductor segments.

Specifically, as shown in FIG. 9, a conductor segment 40 has a basicconfiguration which is substantially letter-U shaped, and includes apair of linear portions 41, and a turn portion 42 which joins a firstend portion of each of the pair of linear portions 41. Then, in a statewhere the conductor segments 40 are inserted into the correspondingslots 34 at an interval representing a prescribed number of slots,bending the second end portions of the linear portions 41 in the corecircumferential direction, and then joining the linear portions 41 ofthe different conductor segments 40 to each other. Each of the slots 34accommodates two conductors which are comprised of the linear portions41 of the conductor segments 40.

As shown in FIG. 3, the turn portions 42 of the conductor segments 40constitute a first coil end 51 at a first axial end of the stator 23,and the joined linear portions 41 of the conductor segments 40constitute a second coil end 52 at an opposite second axial end of thestator 23.

FIG. 7 schematically illustrates only the U1-phase winding of the statorwindings 11 and the U2-phase winding 12 of the stator windings 12, whichare the different-group windings and the same-phase windings, extractedfrom the connection diagram in FIG. 6.

In FIG. 7, the solid line represents the U1-phase winding, and thebroken line represents the U2-phase winding.

The portions of each conductor segment 40 that constitutes the U1-phasewinding are disposed in the stator core 35 at an interval of threeslots, and the portions of each conductor segment 41 that constitutesthe U2-phase winding are disposed in the stator core 35 at an intervalof three slots. Two conductor segments 40 are connected to each other atan interval of nine slots at the second coil end 52. In this case, inthe stator windings 11 and 12, the slot interval at the second coil end52, that is, the nine slot interval, is three times greater than theslot interval at the first coil ends 51, that is, three slot interval;the number (three) of times corresponds to the number (three) of phasesof each of the first and second sets of the stator windings 11 and 12.

FIG. 8 schematically illustrates only the stator windings 11 extractedfrom the stator windings 11 and 12 of the connection diagram in FIG. 6.

In FIG. 8, the solid line represents the U1-phase winding, the brokenline represents the V1-phase winding, and the dashed-dotted linerepresents the W1-phase winding.

The U1-phase, V1-phase, and W1-phase windings of the stator windings 11are equally wound around the stator core 35 so as to partition the core35 in its circumferential direction into three parts.

That is, the phase windings, which are adjacent in terms of energizationsequence, are wound around the stator core 35 at constant-slotintervals, that is, eight (8)-slot intervals, in the circumferentialdirection.

The adjacent phase windings are offset by the 8-slot interval in thecircumferential direction, and the winding pattern of each phase is thesame as that of the other one of the phases. The offset in the windingpatterns of the phase windings is a prescribed electric angle of 120electrical degrees offset in the energization sequence.

In the stator windings 11, the circumferential direction windingintervals between U1 and V1, V1 and W1, and W1 and U1 are identical, andin the stator winding 12, the circumferential direction windingintervals between U2 and V2, V2 and W2, and W2 and U2 are identical.

Next, the following describes how the controller 15 performsenergization control of the stator windings 11 and 12.

The controller 15 of the first embodiment is configured to control thepolarity of energization of the same-phase and different-group windingsdisposed in each mixed-group slot 34B, thus switches the number of polesof the rotary electric machine 10.

Specifically, the controller 15 executes

1. A first energization control that energizes the different-group phasewindings, i.e. conductors, disposed in each mixed-group slot 34B in thesame energization direction

2. A second energization control that energizes the different-groupphase windings, i.e. conductors, disposed in each mixed-group slot 34Bsuch that the energization direction of one of the different-group phasewindings in each mixed-group slot 34B is reversed against theenergization direction of the other of the different-group phasewindings in the corresponding mixed-group slot 34B

3. Switching between execution of the first energization control and thesecond energization control

The controller 15 of the first embodiment is capable of switchingbetween an 8-pole mode in which the number of poles of the rotaryelectric machine 10 is 8, and a 4-pole mode in which the number of polesof the rotary electric machine 10 is 4.

For driving the rotary electric machine 10 in the 8-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 1, to flow through the respectivephase windings:[Equations 1]IU1=A·sin(ωt+α11)IV1=A·sin(ωt+α11−2π/3)IW1=A·sin(ωt+α11+2π/3)IU2=A·sin(ωt+α11)IV2=A·sin(ωt+α11−2π/3)IW2=A·sin(ωt+α11+2π/3)  (1)

where:

A represents the amplitude of each of the currents;

ω represents an electrical angular frequency (rad/sec) of the rotaryelectric machine 10 during the 8-pole mode; and

α represents a phase of the corresponding current.

For driving the rotary electric machine 10 in the 4-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 2, to flow through the respectivephase windings:IU1=A·sin(ωt/2+α12)IV1=A·sin(ωt/2+α12+2π/3)IW1=A·sin(ωt/2+α12−2π/3)IU2=−A·sin(ωt/2+α12)IV2=−A·sin(ωt/2+α12+2π/3)IW2=−A·sin(ωt/2+α12−2π/3)  [Equations 2]

FIG. 10 and FIG. 11 are diagrams showing the energization state of thephase windings in each slot 34, and the U-phase, V-phase, and W-phasemagnetomotive force waveforms. FIG. 10 shows the magnetomotive forcewaveforms in the 8-pole mode, and FIG. 11 shows the magnetomotive forcewaveform in the 4-pole mode. Each of FIGS. 10 and 11 shows half of theslots 34, i.e. #1 slot 34 to #12 slot 34, in a developed view. Thepresence or absence of an underline below each phase indicates adifference in the energization direction.

In FIG. 10, for example, with respect to the U-phase, a current flows inthe phase windings disposed in each of the #1, #4, #7, and #10 slots 34in the same direction. The direction of corresponding magnetomotiveforce in each of the #1, #4, #7, and #10 slots 34 is reversed accordingto the directions of the currents flowing in the corresponding one ofthe #1, #4, #7, and #10 slots 34.

At this time, the energization direction of each of the U1-phase andU2-phase windings in the #4 slot 34, i.e. the mixed-group slot 34B, isidentical to the energization direction of the corresponding one of theU1-phase and U2-phase windings in the #10 slot 34. Consequently, theU-phase magnetic pole is reversed at each of the single-group slots 34A(#1 and #7) and the mixed-group slots 34B (#4 and #10).

The above descriptions for the U-phase can be applied to the V-phase andthe W-phase.

For the V-phase, the V-phase magnetic pole is reversed at each of thesingle-group slots 34A (#3 and #9) and the mixed-group slots 34B (#6 and#12).

For the W-phase, the W-phase magnetic pole is reversed at each of thesingle-group slots 34A (#5 and #11) and the mixed-group slots 34B (#2and #8).

As a result of the energization shown in FIG. 10 above, themagnetomotive force distribution of the stator 23 becomes a full-pitch8-pole distribution, and the rotary electric machine 10 is driven in the8-pole mode.

In FIG. 11, for example, with respect to the U-phase, a current flows,in the same direction, in the two-group phase windings disposed in eachof the #1 and #7 slots 34, which are the single-group slots 34A, in the#1, #4, #7, and #10 slots 34. In contrast, currents flow, in oppositedirections, in the respective two-group phase windings disposed in eachof the #4 and #10 slots 34, which are the mixed-group slots 34B, in the#1, #4, #7, and #10 slots 34.

At this time, in each of the #4 and #10 slots 34, which is acorresponding mixed-group slot 34B, the magnetomotive forces generatedas a result of energization of the two-group phase windings disposed ineach of the #4 and #10 slots 34 cancel one another out. Consequently,the U-phase magnetic poles are reversed in each of the single-groupslots 34A (#1 and #7).

The above descriptions for the U-phase can be applied to the V-phase andthe W-phase.

For the V-phase, the V-phase magnetic poles are reversed in only thesingle-group slots 34A (#3 and #9). Furthermore, for the W-phase, theW-phase magnetic poles are reversed in only the single-group slots 34A(#5 and #11).

As a result of the energization shown in FIG. 11 above, themagnetomotive force distribution of the stator 23 becomes a 4-poledistribution, and the rotary electric machine 10 is driven in the 4-polemode.

In each of the mixed-group slots 34B, as shown in the equations 1 and 2above, the phase of the current flowing in one of the two-group phasewindings is reversed with the phase of the current flowing in the otherof the two-group phase windings.

Furthermore, in the equation 2 above, the energization frequency withrespect to each phase winding is halved relative to the equation 1above. As a result, operations of the rotary electric machine 10 can beperformed at a desired rotation speed even if the electrical angle phaseof a power change varies with switching from the 8-pole mode to the4-pole mode.

The controller 15 switches the number of poles of the rotary electricmachine 10 in accordance with the torque characteristics in the 8-polemode and the torque characteristics in the 4-pole mode.

Specifically, as shown in FIG. 12, the 8-pole mode enables the torque ofthe rotary electric machine 10 to be higher in the low-rotation regionthan the 4-pole mode, and the 4-pole mode enables the torque of therotary electric machine 10 to be higher in the high-rotation region thanthe 8-pole mode.

On the basis of these torque characteristics, the controller 15, forexample, performs 8-pole energization control in the region below apredetermined rotational speed Nx, and performs 4-pole energizationcontrol in the region equal to or more than the above the rotationalspeed Nx.

In accordance with the vehicle travelling state, the controller 15switches the number of poles of the rotary electric machine 10 from oneof the 8-pole mode and the 4-pole mode to the other thereof in responseto a vehicle drive request.

For example, the controller 15 switches the number of poles of therotary electric machine 10 from the 4-pole mode to the 8-pole mode(higher-pole mode) to thereby output higher torque during low-speedrunning or at startup. In contrast, the controller 15 switches thenumber of poles of the rotary electric machine 10 from the 8-pole modeto the 4-pole mode (lower-pole mode) to thereby cause the vehicle totravel at a higher speed during high-speed travelling.

FIG. 13 is a flowchart showing an energization control routine for therotary electric machine 10, which is performed by the controller 15every predetermined period.

In FIG. 13, the controller 15 determines whether the controller 15should perform the 8-pole mode in step S11. At this time, for example,if the vehicle 100 is currently traveling at low speeds or is beingstarted, the controller 15 determines that the controller 15 shouldperform the 8-pole mode (YES in step S11), and the routine proceeds tostep S12.

In step S12, the controller 15 controls the phase current that flows ineach stator windings 11 and 12 in accordance with the equations 1 above,thus causing the rotary electric machine 10 to perform in the 8-polemode.

This causes each current to flow through the corresponding one of thetwo group-windings disposed in each of the mixed-group slots 34B in thesame direction.

Otherwise, upon determination that the controller 15 should not performthe 8-pole mode (NO in step S11), the controller 15 determines whetherthe controller 15 should perform the 4-pole mode in step S13. At thistime, for example, if the vehicle 100 is currently traveling at highspeeds, the controller 15 determines that the controller 15 shouldperform the 4-pole mode (YES in step S13), and the routine proceeds tostep S14.

In step S14, the controller 15 controls the phase current that flows ineach stator windings 11 and 12 in accordance with the equations 2 above,thus causing the rotary electric machine 10 to perform in the 4-polemode.

This causes currents to flow through the corresponding respective twogroup-windings disposed in each of the mixed-group slots 34B in theopposite directions from one another.

Note that the operations in steps S11 and S13 correspond to a switchingunit, the operation in step S12 corresponds to a first energizationcontrol unit, and the operation in step S14 corresponds to a secondenergization control unit.

The present embodiment described in detail above obtains the followingsuperior effects.

The first embodiment includes the single-group slots 34A and mixed-groupslots 34B of the stator core 35, and is configured to control theenergization direction of each of the stator windings disposed in eachof the slots 34A and 34B to thereby change the number of poles of therotary electric machine 10. This enables the operating range of therotary electric machine 10 to expand.

The first embodiment is configured such that the three-phase windingsare would around the stator core 35 with identical winding intervalsbetween the adjacent phases of the three-phase windings. This enableselectromagnetic forces generated by the respective three-phase windingsto be identical to each other regardless of the pole-number mode of therotary electric machine 10.

Consequently, torque ripples that arise due to circumferential directionimbalances in the magnetomotive forces are reduced, and reductions invibrations and noise can be achieved. Furthermore, because variations inthe phase voltages can be suppressed for the same reason, the high-speedoperating range can be further expanded.

The first embodiment is configured such that the single-group slots 34Aand the mixed-group slots 34B are alternatingly disposed in the statorcore 35.

In other words, the single-group slots 34A, which respectively have thedifferent first and second groups, are arranged at two-slot intervals inthe core circumferential direction, and each mixed-group slot 34B isarranged between a corresponding pair of the single-group slots 34A,which respectively have the different first and second groups.

This configuration enables the slots in each of which magnetomotiveforce is generated, that is, the slots in each of which the energizationdirections of the two-group phase windings are identical, are arrangedto be equally spaced in the core circumferential direction, regardlessof the pole-number mode (8-pole mode or 4-pole mode) of the rotaryelectric machine 10.

As a result, the magnetomotive force can be generated in a well-balancedfashion in the circumferential direction, regardless of the pole numbermode.

The first embodiment is configured such that the number of one or morefirst-group windings, which is one as an example in the firstembodiment, and the number of one or more second-group windings, whichis one as an example in the first embodiment, disposed in eachmixed-group slot 34B are set to be identical to one another. Thisenables the respective phase windings to be energized using thecorresponding phase currents having a same amplitude. This enables thevoltage and current rating of each phase of the first inverter 13 to beidentical to that of the corresponding phase of the second inverter 14,making it possible to achieve commonality of components of the first andsecond inverters 13 and 14, resulting in reduction in cost of the firstand second inverters 13 and 14.

The first embodiment is configured to perform

1. The first energization control that energizes the different-groupphase windings disposed in each mixed-group slot 34B in the sameenergization direction

2. The second energization control that energizes the different-groupphase windings disposed in each mixed-group slot 34B such that theenergization direction of one of the different-group phase windings ineach mixed-group slot 34B is reversed against the energization directionof the other of the different-group phase windings in the correspondingmixed-group slot 34B

3. Appropriately switching between execution of the first energizationcontrol and the second energization control

This configuration makes it possible to switch between

1. A first state in which the magnetomotive forces of the phase windingsincluded in each single-group slot 34A are added to each other and themagnetomotive forces of the phase windings included in each mixed-groupslot 34B are added to each other

2. A second state in which the magnetomotive forces of the phasewindings included only in each single-group slot 34A are added to eachother, so that the magnetomotive forces of the phase windings includedin each mixed-group slot 34B cancel each other out

As a result, it is possible to appropriately switch the number of polesof the rotary electric machine 10 according to, for example, a driverequest with respect to the rotary electric machine 10.

The first embodiment is configured to drive the rotary electric machine10 in the 8-pole mode in the low-rotational speed range, and drive therotary electric machine 10 in the 4-pole mode in the high-rotationalspeed range.

Consequently, when the rotary electric machine 10 is used for driving avehicle, appropriate driving can be carried out when both low-speedhigh-torque operation and high-speed operation are required for therotary electric machine 10.

The first embodiment is configured to, when switching the 8-pole mode tothe 4-pole mode, reduce the energization frequency applied to each ofthe phase windings such that the frequency in the 4-pole mode is halfthat in the 8-pole mode. As a result, operations of the rotary electricmachine 10 can be performed at a desired rotation speed even if theelectrical angle phase of a power change varies with switching from the8-pole mode to the 4-pole mode.

In the vehicle 100, the number of poles of the rotary electric machine10 is switched by motor current control, the operating range of therotary electric machine 10 can be expanded without increasing thebattery capacity. This enables the size, weight, and manufacturing costof the rotary electric machine system to be reduced. Furthermore, fuelconsumption of the vehicle 100 can be improved resulting from expansionof the motor power running region and regeneration region.

In the configuration where the rotary electric machine 10 serves as aninduction machine, the number of poles of the rotor 22 can be switchedaccording to the number of poles of the stator 23.

This configuration makes it possible to use, as the rotor 22, a normallyavailable rotor, such as a cage-type rotor, which has a simple androbust structure. This results in the rotary electric machine 10featuring simpler maintenance, higher reliability, and lower cost.

The following describes the other embodiments. For convenience, thefollowing describes mainly the different points between the firstembodiment and each of the other embodiments.

Second Embodiment

The number of slots in the rotary electric machine 10 can be changed,for example, such that the number of slots is doubled.

As illustrated in FIG. 14, the stator core 35 of the second embodimentis comprised of 48 slots 34 that are arranged with regular intervals inthe circumferential direction of the core 35. Slots numbers #1 to #48are assigned to the respective 48 slots 34.

The stator windings 11 and 12 are would in corresponding slots in theslots 34 such that two portions selected from at least one of the statorwindings 11 and the stator windings 12 are disposed in the respectiveinner side and outer side of each slot 34.

In FIG. 14, the portions of the first group of stator windings 11 arerepresented by darker shading than the portions of the second group ofstator windings 12.

Like the first embodiment, the slots 34 of the stator core 35 of therotary electric machine 10 according to the second embodiment includethe single-group slots 34A and the mixed-group slots 34B.

In each of the single-winding slots 34A, portions of the same phasewinding in the same group are disposed; the direction of a currentflowing through one of these portions is identical to the direction of acurrent flowing through the other thereof.

In each of the mixed-winding slots 34B, portions of the same phasewindings in the respective different groups are disposed. Thesingle-group slots 34A are arranged at predetermined intervals in thecircumferential direction of the stator core 35, and the mixed-groupslots 34B are arranged at predetermined intervals in the circumferentialdirection of the stator core 35. In FIG. 14, two of the single-groupslots 34A and two of the mixed-group slots 34B are alternatinglyarranged.

For example, the #1 and #2 slots serve as slots of the single-groupslots 34A, and the #3 and #4 slots serve as slots of the mixed-groupslots 34B.

Like the first embodiment, the second embodiment is configured toenergize the different-group same-phase windings disposed in eachmixed-group slot 34B such that the energization direction of one of thedifferent-group phase windings in each mixed-group slot 34B is reversedagainst the energization direction of the other of the different-groupphase windings in the corresponding mixed-group slot 34B. This changesthe number of poles of the rotary electric machine 10.

FIG. 15 shows the winding state of the stator windings 11 and 12 withrespect to the #1 to #48 slots 34.

FIG. 16 and FIG. 17 are diagrams showing the energization state of thephase windings in each slot 34, and the U-phase, V-phase, and W-phasemagnetomotive force waveforms. FIG. 16 shows the magnetomotive forcewaveforms in the 8-pole mode, and FIG. 17 shows the magnetomotive forcewaveform in the 4-pole mode. Each of FIGS. 16 and 17 shows half of theslots 34, i.e. #1 slot 34 to #12 slot 34, in a developed view.

In FIG. 15, the U1-phase, V1-phase, and W1-phase windings of the statorwindings 11 are equally wound around the stator core 35 so as topartition the core 35 in its circumferential direction into three parts.Similarly, the U2-phase, V2-phase, and W2-phase windings of the statorwindings 12 are equally wound around the stator core 35 so as topartition the core 35 in its circumferential direction into three parts.

That is, the phase windings, which are adjacent in terms of energizationsequence, are wound around the stator core 35 at constant-slotintervals, that is, sixteen (16)-slot intervals, in the circumferentialdirection.

The adjacent phase windings are offset by the 16-slot interval in thecircumferential direction, and the winding pattern of each phase is thesame as that of the other one of the phases.

In the 8-pole mode illustrated in FIG. 16, for example, with respect tothe U-phase, the energization direction of each of the U1-phase andU2-phase windings in the #7 slot 34, i.e. the mixed-group slot 34B, isidentical to the energization direction of the corresponding one of theU1-phase and U2-phase windings in the #8 slot 34. Similarly, theenergization direction of each of the U1-phase and U2-phase windings inthe #19 slot 34, i.e. the mixed-group slot 34B, is identical to theenergization direction of the corresponding one of the U1-phase andU2-phase windings in the #20 slot 34.

Consequently, the U-phase magnetic pole is reversed at each of

1. The first set of single-group slots 34A (#1 and #2)

2. The second set of single-group slots 34A (#13 and #14)

3. The third set of mixed-group slots 34B (#7 and #8)

4. The fourth set of mixed-group slots 34B (#19 and #20)

The above descriptions for the U-phase can be applied to the V-phase andthe W-phase.

As a result of the energization shown in FIG. 16 above, themagnetomotive force distribution of the stator 23 becomes a full-pitch8-pole distribution, and the rotary electric machine 10 is driven in the8-pole mode.

In contrast, in the 4-pole mode illustrated in FIG. 17, for example,with respect to the U-phase, currents flow, in opposite directions, inthe respective two-group phase windings disposed in each of the #7 and#8 slots 34 and #19 and #20 slots, which are the mixed-group slots 34B.

At this time, in each of the #7 and #8 slots 34 and #19 and #20 slots34, the magnetomotive forces generated as a result of energization ofthe two-group phase windings disposed in each of the #7 and #8 slots 34and #19 and #20 slots 34 cancel one another out. Consequently, theU-phase magnetic poles are reversed in each of the

1. The first set of single-group slots 34A (#1 and #2)

2. The second set of single-group slots 34A (#13 and #14)

The above descriptions for the U-phase can be applied to the V-phase andthe W-phase.

As a result of the energization shown in FIG. 17 above, themagnetomotive force distribution of the stator 23 becomes a 4-poledistribution, and the rotary electric machine 10 is driven in the 4-polemode.

Like the first embodiment, the second embodiment is configured tocontrol the energization direction of each of the stator windingsdisposed in each of the slots 34A and 34B to thereby change the numberof poles of the rotary electric machine 10. This enables the operatingrange of the rotary electric machine 10 to expand.

The first embodiment is configured such that the three-phase windingsare would around the stator core 35 with identical winding intervalsbetween the adjacent phases of the three-phase windings. This enableselectromagnetic forces generated by the respective three-phase windingsto be identical to each other, resulting in reduction in torque ripplesand in expansion of the high-speed operating range.

The second embodiment is configured such that two of the single-groupslots 34A and two of the mixed-group slots 34B are alternatinglydisposed in the stator core 35. In other words, the single-group slots34A, which respectively have the different first and second groups, arearranged at three-slot intervals in the core circumferential direction,and each two of the mixed-group slots 34B is arranged between acorresponding pair of the single-group slots 34A, which respectivelyhave the different first and second groups.

This configuration enables the slots in each of which magnetomotiveforce is generated, that is, the slots in each of which the energizationdirections of the two-group phase windings are identical, are arrangedto be equally spaced in the core circumferential direction, regardlessof the pole-number mode (8-pole mode or 4-pole mode) of the rotaryelectric machine 10.

As a result, the magnetomotive force can be generated in a well-balancedfashion in the circumferential direction, regardless of the pole numbermode.

Each of the stator windings 11 and 12 may be configured as a short-pitchwinding, the detailed configuration of which is shown in FIG. 18.

Reference character (a) of FIG. 18 shows an energization state whenenergization is performed in the 8-pole mode, and reference character(b) of FIG. 18 shows an energization state when energization isperformed in the 4-pole mode.

In FIG. 18, the energization pattern of the slots for each of the 8- and4-pole modes is the same as that for the corresponding one of the 8-polemode (see FIG. 16) and the 4-pole mode (see FIG. 17), and the differenceis that each of the phase windings on the inner radial side of the slots34 is offset by one slot to obtain a short-pitch winding.

Each of the stator windings 11 and 12 may be configured as a long-pitchwinding, the detailed configuration of which is shown in FIG. 19.

Reference character (a) of FIG. 19 shows an energization state whenenergization is performed in the 8-pole mode, and reference character(b) of FIG. 19 shows an energization state when energization isperformed in the 4-pole mode.

In FIG. 19, the energization pattern of the slots for each of the 8- and4-pole modes is the same as that for the corresponding one of the 8-polemode (see FIG. 16) and the 4-pole mode (see FIG. 17), and the differenceis that each of the phase windings on the inner radial side of the slots34 is offset by one slot to obtain a full-pitch winding.

Third Embodiment

The third embodiment is configured to be capable of switching the16-pole mode to the 4-pole mode. In this case, the number of poles ofthe rotary electric machine 10 is switched based on a pole number ratioof 4:1.

FIG. 20 and FIG. 21 show the energization state of the phase windings ineach slot 34, and the waveform of the resultant magnetomotive force(U+V+W) of the U-phase, V-phase, and W-phase magnetomotive forces.

FIG. 20 shows the waveform of the resultant magnetomotive force (U+V+W)in the 16-pole mode, and FIG. 21 shows the waveform of the resultantmagnetomotive force (U+V+W) in the 4-pole mode. Each of FIGS. 20 and 21shows half of the slots 34 in a developed view.

Referring to FIG. 20, the single-group slots 34A, which respectivelyhave the different first and second groups, are arranged at four-slotintervals in the core circumferential direction, and each three of themixed-group slots 34B is arranged between a corresponding pair of thesingle-group slots 34A, which respectively have the different first andsecond groups.

In the 16-pole mode illustrated in FIG. 20, the energization directionof one of the different-group phase windings in each of the mixed-groupslot 34B is identical to the energization direction of the other of thedifferent-group phase windings.

Consequently, at each of the single-group slots 34A and mixed-groupslots 34B, the corresponding magnetic pole is reversed.

As a result of the energization shown in FIG. 20 above, themagnetomotive force distribution of the stator 23 becomes a full-pitch16-pole distribution, and the rotary electric machine 10 is driven inthe 16-pole mode.

In contrast, in the 4-pole mode illustrated in FIG. 21, currents flow,in opposite directions, in the respective two-group phase windingsdisposed in each of the mixed-group slots 34B. For this reason, themagnetomotive forces generated as a result of energization of thetwo-group phase windings disposed in each of the mixed-group slots 34Bcancel one another out. Consequently, the U-phase magnetic poles arereversed in each of the single-group slots 34A.

As a result of the energization shown in FIG. 21 above, themagnetomotive force distribution of the stator 23 becomes a 4-poledistribution, and the rotary electric machine 10 is driven in the 4-polemode.

For driving the rotary electric machine 10 in the 16-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 3, to flow through the respectivephase windings:IU1=A·sin(2)t+α11)IV1=A·sin(2)t+α11−2π/3)IW1=A·sin(2)t+α11+2π/3)IU2=A·sin(2)t+α11)IV2=A·sin(2)t+α11−2π/3)IW2=A·sin(2)t+α11+2π/3)  [Equations 3]

Similarly, for driving the rotary electric machine 10 in the 4-polemode, the controller 15 causes the following electrical currents, whichare expressed by the following equations 4 identical to the respectiveequations (2), to flow through the respective phase windings:IU1=A·sin(ωt/2+α12)IV1=A·sin(ωt/2+α12+2π/3)IW1=A·sin(ωt/2+α12−2π/3)IU2=−A·sin(ωt/2+α12)IV2=−A·sin(ωt/2+α12+2π/3)IW2=−A·sin(ωt/2+α12−2π/3)  [Equations 4]

Note that the electric angle frequency ω is doubled in the equations 3,and the electric angle frequency ω is halved in the equation 4, howeverthe electric angle frequency ω may instead be kept unchanged in theequations 3, and the electric angle frequency ω may be quartered in theequations 4. In other words, the electric angle frequency ω in the4-pole mode is made one quarter of that of the 16-pole mode. Inaddition, it is also possible to halve the electric angle frequency ω inthe 4-pole mode as compared with the electric angle frequency ω in the16-pole mode.

Fourth Embodiment

The fourth embodiment has a configuration in which a first pair ofdifferent-group phase windings and a second pair of different-groupphase windings are disposed in each of the mixed-group slots 34B.

As illustrated in FIG. 22, the stator core 35 of the fourth embodimentis comprised of 24 slots 34 that are arranged with regular intervals inthe circumferential direction of the core 35. Slots numbers #1 to #24are assigned to the respective 24 slots 34.

The stator windings 11 and 12 are would in corresponding slots in theslots 34 such that four portions selected from at least one of thestator windings 11 and the stator windings 12 are disposed in therespective inner side and outer side of each slot 34.

In FIG. 22, the portions of the first group of stator windings 11 arerepresented by darker shading than the portions of the second group ofstator windings 12.

Like the first embodiment, the slots 34 of the stator core 35 of therotary electric machine 10 according to the fourth embodiment includethe single-group slots 34A and the mixed-group slots 34B.

In each of the single-winding slots 34A, portions of the same phasewinding in the same group are disposed; the direction of a currentflowing through one of these portions is identical to the direction of acurrent flowing through the other thereof.

In each of the mixed-winding slots 34B, portions of the same phasewindings in the respective different groups are disposed. Thesingle-group slots 34A are arranged at predetermined intervals in thecircumferential direction of the stator core 35, and the mixed-groupslots 34B are arranged at predetermined intervals in the circumferentialdirection of the stator core 35.

In FIG. 14, two of the single-group slots 34A and two of the mixed-groupslots 34B are alternatingly arranged.

In particular, each single-group slot 34A accommodates four phasewindings (conductors) of the same group and the same phase, and eachmixed-group slot 34B accommodates a first pair of two phase windings(conductors) with the same phase in the respective different groups, anda second pair of two phase windings with the same phase in therespective different groups.

The single-group slots 34A and the mixed-group slots 34B arealternatingly arranged in the stator core 35.

Like each of the above embodiments, the fourth embodiment is configuredto energize the different-group same-phase windings disposed in eachmixed-group slot 34B such that the energization direction of one of thedifferent-group same-phase windings in each mixed-group slot 34B isreversed against the energization direction of the other of thedifferent-group same-phase windings in the corresponding mixed-groupslot 34B. This changes the number of poles of the rotary electricmachine 10. The number of phase windings (conductors) accommodated ineach slot 34 is freely determined as long as the number is an evennumber, and, for example, each slot 34 can be configured to accommodatesix or eight phase windings.

FIG. 23 and FIG. 24 show the energization state of the phase windings ineach slot 34, and the waveform of the resultant magnetomotive force(U+V+W) of the U-phase, V-phase, and W-phase magnetomotive forces.

FIG. 23 shows the waveform of the resultant magnetomotive force (U+V+W)in the 8-pole mode, and FIG. 24 shows the waveform of the resultantmagnetomotive force (U+V+W) in the 4-pole mode. Each of FIGS. 23 and 24shows half of the slots 34 in a developed view.

Referring to FIG. 23, the energization directions of the respectivedifferent-group phase windings in each of the mixed-group slot 34B areidentical to one another.

Consequently, at each of the single-group slots 34A and mixed-groupslots 34B, the corresponding magnetic pole is reversed.

As a result of the energization shown in FIG. 23 above, themagnetomotive force distribution of the stator 23 becomes a full-pitch8-pole distribution, and the rotary electric machine 10 is driven in the8-pole mode.

In contrast, in the 4-pole mode illustrated in FIG. 24, currents flow,in opposite directions, in the respective two-group phase windings ofeach of the first and second pairs disposed in each of the mixed-groupslots 34B. For this reason, the magnetomotive forces generated as aresult of energization of the two-group phase windings of each of thefirst and second pairs disposed in each of the mixed-group slots 34Bcancel one another out. Consequently, the U-phase magnetic poles arereversed in each of the single-group slots 34A.

As a result of the energization shown in FIG. 24 above, themagnetomotive force distribution of the stator 23 becomes a 4-poledistribution, and the rotary electric machine 10 is driven in the 4-polemode.

Fifth Embodiment

In the fifth embodiment, four groups of stator windings (phase windings)are wound around the stator core 35 in the rotary electric machine 10.

In addition, as shown in FIG. 25, four inverters 61 to 64 are providedwhich respectively correspond to the four groups (first to fourthgroups) of stator windings. The inverters 61 to 64 each correspond to apower converter.

The inverters 61 to 64 may be configured as a single power convertor.The fifth embodiment can be configured to control a current to besupplied to each of the three-phase windings of each of the four groupsof stator windings to thereby change the number of poles of the rotaryelectric machine 10 in three steps.

If the fifth embodiment is configured to include 2{circumflex over( )}(A−1) groups of phase windings, and to change the number of poles ofthe rotary electric machine 10 in A-steps, the number of A is set to 3.

The fifth embodiment is configured to switch among the 16-pole mode, inwhich the number of poles of the machine 10 is set to 16, the 4-polemode, in which the number of poles of the machine 10 is set to 4, andthe 2-pole mode, in which the number of poles of the machine 10 is setto 2.

FIG. 26 to FIG. 28 are diagrams showing energization patterns of thephase windings in each-pole number mode of the 48-slot rotary electricmachine 10.

FIG. 26 shows the energization pattern in the 16-pole mode, FIG. 27shows the energization pattern in the 4-pole mode, and FIG. 28 shows theenergization pattern in the 2-pole mode. The presence or absence of anunderline below each phase indicates a difference in the energizationdirection.

In the fifth embodiment, among the #1 to #48 slots, each of the #1, #9,#17, #25, #33, and #41 slots serves as a corresponding one of thesingle-group slots, and all of the other slots respectively serve as themixed-group slots.

In this case, a selected one of the first-group phase windings and aselected one of the fourth-group phase windings are disposed in each ofthe single-group slots.

In each mixed-group slot, selected two different-group and same-phasewindings are disposed. In each mixed-group slot, a unique combination ofany two-different group windings selected from the first to fourthgroups is set to be different from that in the other one of themixed-group slots.

That is, the mixed-group slots include respective different combinationsof two-different group windings selected from the first to fourthgroups.

Additionally, the mixed-group slots include, for each phase, three (n−1)types of combinations of any two-different group windings selected fromthe first to fourth groups. For the U-phase, the mixed-group slotsinclude a first type of combination of U1- and U2-windings, a secondtype of combination of U2- and U3-windings, and a third type ofcombination of U3- and U4-windings.

For convenience of description, the slots that correspond to thesingle-group slots in FIG. 26 are shown shaded.

Furthermore, in FIG. 27 and FIG. 28, among the mixed-group slots, themixed-group slots in which the energization directions of the two groupsof phase windings are identical (that is, slots in which magnetomotiveforce is generated) are shown shaded in addition to the single-groupslots.

In the 16-pole mode shown in FIG. 26, the energization directions of thetwo groups of phase windings in each of the mixed-group slots areidentical to each other. Consequently, the respective magnetic poles arereversed in each of the single-group slots and in each of themixed-group slots. As a result, the magnetomotive force distribution ofthe stator 23 becomes a full-pitch 16-pole distribution, and the rotaryelectric machine 10 is driven in the 16-pole mode.

In the 4-pole mode shown in FIG. 27, among all of the mixed-group slots,the energization directions of the two groups of phase windings areidentical in the #5, #13, #21, #29, #37, and #45 slots (shadedmixed-group slots), which accommodate the second group and the thirdgroup of phase windings.

That is, the respective magnetic poles are reversed in the single-groupslots and the #5, #13, #21, #29, #37, and #45 mixed-group slotsdescribed above. As a result, the magnetomotive force distribution ofthe stator 23 becomes a full-pitch 4-pole distribution, and the rotaryelectric machine 10 is driven in the 4-pole mode.

In the 2-pole mode shown in FIG. 28, the energization directions of thetwo groups of phase windings are different for all of the mixed-groupslots. In this case, the magnetic poles are reversed in each of thesingle-group slots. As a result, the magnetomotive force distribution ofthe stator 23 becomes a full-pitch 2-pole distribution, and the rotaryelectric machine 10 is driven in the 2-pole mode.

For driving the rotary electric machine 10 in the 16-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 5, to flow through the respectivephase windings:IU1=A·sin(2ωt+α21)IV1=A·sin(2ωt+α21−2π/3)IW1=A·sin(2ωt+α21+2π/3)IU2=A·sin(2ωt+α21)IV2=A·sin(2ωt+α21−2π/3)IW2=A·sin(2ωt+α21+2π/3)IU3=A·sin(2ωt+α21)IV3=A·sin(2ωt+α21−2π/3)IW3=A·sin(2ωt+α21+2π/3)IU4=A·sin(2ωt+α21)IV4=A·sin(2ωt+α21−2π/3)IW4=A·sin(2ωt+α21+2π/3)  [Equation 5]

For driving the rotary electric machine 10 in the 4-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 6, to flow through the respectivephase windings:IU1=A·sin(ωt/2+α22)IV1=A·sin(ωt/2+α22−2π/3)IW1=A·sin(ωt/2+α22+2π/3)IU2=−A·sin(ωt/2+α22)IV2=−A·sin(ωt/2+α22−2π/3)IW2=−A·sin(ωt/2+α22+2π/3)IU3=−A·sin(ωt/2+α22)IV3=−A·sin(ωt/2+α22−2π/3)IW3=−A·sin(ωt/2+α22+2π/3)IU4=A·sin(ωt/2+α22)IV4=A·sin(ωt/2+α22−2π/3)IW4=A·sin(ωt/2+α22+2π/3)  [Equation 6]

For driving the rotary electric machine 10 in the 2-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 7, to flow through the respectivephase windings:IU1=A·sin(ωt/4+α23)IV1=A·sin(ωt/4+α23+2π/3)IW1=A·sin(ωt/4+α23−2π/3)IU2=−A·sin(ωt/4+α23)IV2=−A·sin(ωt/4+α23+2π/3)IW2=−A·sin(ωt/4+α23−2π/3)IU3=A·sin(ωt/4+α23)IV3=A·sin(ωt/4+α23+2π/3)IW3=A·sin(ωt/4+α23−2π/3)IU4=−A·sin(ωt/4+α23)IV4=−A·sin(ωt/4+α23+2π/3)IW4=−A·sin(ωt/4+α23−2π/3)  [Equation 7]

Here, a supplementary description of the energization control in eachpole number mode is provided. In the 16-pole mode, as can be understoodfrom Equation 5 above, the controller 15 causes the directions of theenergization currents of each group and each phase to all be identical.As a result, as shown in FIG. 26, the energization directions of the twogroups of phase windings in the same slot become identical in thesingle-group slots and all of the mixed-group slots, and the number ofpoles of the rotary electric machine 10 becomes a maximum value (16poles).

Furthermore, in the 4-pole mode, as can be understood from Equation 6above, the controller 15 reverses, among the energization currents ofeach group and each phase, the direction of the energization currents ofthe second group and the third group (IU2, IV2, IW2, IU3, IV3, and IW3).In this case, for example, among the U1-U2, U2-U3, and U3-U4combinations of phase windings in the U-phase mixed-group slots, theenergization directions become identical for the U2-U3 combination, andthe energization directions are mutually opposing for the U1-U2 andU3-U4 combinations. As a result, as shown in FIG. 27, the energizationdirections of the two groups of phase windings in the same slot becomeidentical in the single-group slots and some of the mixed-group slots(mixed-group slots which are combinations of the second and thirdgroup), and the number of poles of the rotary electric machine 10becomes 4 poles.

Furthermore, in the 2-pole mode, as can be understood from Equation 7above, the controller 15 reverses, among the energization currents ofeach group and each phase, the direction of the energization currents ofthe second group and the fourth group (IU2, IV2, IW2, IU4, IV4, andIW4). In this case, for example, the energization directions aremutually opposing for all of the U1-U2, U2-U3, and U3-U4 combinations ofphase windings in the U-phase mixed-group slots. As a result, as shownin FIG. 28, the energization directions of the two groups of phasewindings in the same slot become identical in only the single-groupslots, and the number of poles of the rotary electric machine 10 becomes2 poles.

In other words, as shown in FIG. 26 to FIG. 28, the controller 15selectively executes, at the time of energization of the phase windings,a first task (see FIG. 27) which causes the energization directions ofthe phase windings in some of the mixed-group slots to become different,and a second task (see FIG. 28) which causes the energization directionsof the phase windings in all of the mixed-group slots to becomedifferent.

According to the above configuration of the present embodiment, the twogroups of phase windings accommodated in the mixed-group slots representthree different types of combinations for each phase. In this case, byusing the mixed-group slots having three types of combinations for eachphase, and appropriately energizing the mixed-group slots, anadvantageous configuration can be realized when implementing a polenumber ratio having multiple levels.

Furthermore, because a configuration is used that selectively executes,at the time of energization of the phase windings, a first task whichcauses the energization directions of the phase windings in some of themixed-group slots to become different, and a second task which causesthe energization directions of the phase windings in all of themixed-group slots to become different, the number of poles in the rotaryelectric machine 10 can be appropriately switched in three or more steps

The inverters 61 to 64 are provided to the four groups of phasewindings, and the controller 15 performs power conversion with respectto each of the inverters 61 to 64 to control the energization of thephase windings in the rotary electric machine 10. In this case, becauseeach group of phase windings is driven in parallel by individualinverters 61 to 64, redundancy can be ensured when the rotary electricmachine 10 is driven.

Sixth Embodiment

In the sixth embodiment, eight groups of stator windings (phasewindings) are wound around the stator core 35 in the rotary electricmachine 10.

In addition, as shown in FIG. 29, eight inverters 71 to 78 are providedwhich respectively correspond to eight groups (first to eighth groups)of stator windings. The inverters 71 to 78 each correspond to a powerconverter. The sixth embodiment can be configured to control a currentto be supplied to each of the three-phase windings of each of the eightgroups of stator windings to thereby change the number of poles of therotary electric machine 10 in four steps.

If the sixth embodiment is configured to include 2{circumflex over( )}(A−1) groups of phase windings, and to change the number of poles ofthe rotary electric machine 10 in A-steps, the number of A is set to 4.

The sixth embodiment is configured to switch among the 16-pole mode, inwhich the number of poles of the machine 10 is set to 16, the 8-polemode, in which the number of poles of the machine 10 is set to 8, the4-pole mode, in which the number of poles of the machine 10 is set to 4,and the 2-pole mode, in which the number of poles of the machine 10 isset to 2.

FIG. 30 to FIG. 33 are diagrams showing energization patterns of thephase windings in each pole number mode of the 48-slot rotary electricmachine 10.

FIG. 30 shows the energization pattern in the 16-pole mode, FIG. 31shows the energization pattern in the 8-pole mode, FIG. 32 shows theenergization pattern in the 4-pole mode, and FIG. 33 shows theenergization pattern in the 2-pole mode. The presence or absence of anunderline below each phase indicates a difference in the energizationdirection.

In the sixth embodiment, among the #1 to #48 slots, each of #1, #9, #17,#25, #33, and #41 slots serves as a corresponding one of thesingle-group slots, and all of the other slots respectively serve as themixed-group slots.

In this case, a selected one of the first-group phase windings and aselected one of the eighth-group phase windings are disposed in each ofthe single-group slots.

In each mixed-group slot, selected two different-group and same-phasewindings are disposed. In each mixed-group slot, a unique combination ofany two-different group windings selected from the first to eighthgroups is set to be different from that in the other one of themixed-group slots.

That is, the mixed-group slots include respective different combinationsof two-different group windings selected from the first to eighthgroups.

Additionally, the mixed-group slots include, for each phase, seven (n−1)types of combinations of any two-different group windings selected fromthe first to eighth groups.

For convenience of description, the slots that correspond to thesingle-group slots in FIG. 30 are shown shaded.

Furthermore, in FIG. 31 to FIG. 33, among the mixed-group slots, themixed-group slots in which the energization directions of the two groupsof phase windings are identical (that is, slots in which magnetomotiveforce is generated) are shown shaded in addition to the single-groupslots.

In the 16-pole mode shown in FIG. 30, the energization directions of thetwo groups of phase windings are identical for all of the mixed-groupslots.

Consequently, the respective magnetic poles are reversed in thesingle-group slots and the mixed-group slots. As a result, themagnetomotive force distribution of the stator 23 becomes a full-pitch16-pole distribution, and the rotary electric machine 10 is driven inthe 16-pole mode.

In the 8-pole mode shown in FIG. 31, among all of the mixed-group slots,the energization directions of the two groups of phase windings areidentical in

1. The #7, #11, #23, #27, #39, #43 slots, which accommodate the secondgroup and the third group of phase windings

2. The #5, #13, #21, #29, #37, #45 slots, which accommodate the fourthgroup and the fifth group of phase windings

3. The #3, #15, #19, #31, #35, #47 slots, which accommodate the sixthgroup and seventh group of phase windings (each of which are mixed-groupslots that are shaded)

That is, the respective magnetic poles are reversed in the single-groupslots and the mixed-group slots described above. As a result, themagnetomotive force distribution of the stator 23 becomes a full-pitch8-pole distribution, and the rotary electric machine 10 is driven in the8-pole mode.

In the 4-pole mode shown in FIG. 32, among all of the mixed-group slots,the energization directions of the two groups of phase windings isidentical in the #5, #13, #21, #29, #37, and #45 slots (shadedmixed-group slots), which accommodate the fourth group and the fifthgroup of phase windings.

That is, the respective magnetic poles are reversed in the single-groupslots and the mixed-group slots described above. As a result, themagnetomotive force distribution of the stator 23 becomes a full-pitch4-pole distribution, and the rotary electric machine 10 is driven in the4-pole mode.

In the 2-pole mode shown in FIG. 33, the energization directions of thetwo groups of phase windings are different for all of the mixed-groupslots. In this case, the magnetic poles are reversed in only thesingle-group slots. As a result, the magnetomotive force distribution ofthe stator 23 becomes a full-pitch 2-pole distribution, and the rotaryelectric machine 10 is driven in the 2-pole mode.

For driving the rotary electric machine 10 in the 16-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 8, to flow through the respectivephase windings:IU1=A·sin(2ωt+α31)IV1=A·sin(2ωt+α31−2π/3)IW1=A·sin(2ωt+α31+2π/3)IU2=A·sin(2ωt+α31)IV2=A·sin(2ωt+α31−2π/3)IW2=A·sin(2ωt+α31+2π/3)IU3=A·sin(2ωt+α31)IV3=A·sin(2ωt+α31−2π/3)IW3=A·sin(2ωt+α31+2π/3)IU4=A·sin(2ωt+α31)IV4=A·sin(2ωt+α31−2π/3)IW4=A·sin(2ωt+α31+2π/3)IU5=A·sin(2ωt+α31)IV5=A·sin(2ωt+α31−2π/3)IW5=A·sin(2ωt+α31+2π/3)IU6=A·sin(2ωt+α31)IV6=A·sin(2ωt+α31−2π/3)IW6=A·sin(2ωt+α31+2π/3)IU7=A·sin(2ωt+α31)IV7=A·sin(2ωt+α31−2π/3)IW7=A·sin(2ωt+α31+2π/3)IU8=A·sin(2ωt+α31)IV8=A·sin(2ωt+α31−2π/3)IW8=A·sin(2ωt+α31+2π/3)  [Equation 8]

For driving the rotary electric machine 10 in the 8-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 9, to flow through the respectivephase windings:IU1=A·sin(ωt+α32)IV1=A·sin(ωt+α32+2π/3)IW1=A·sin(ωt+α32−2π/3)IU2=−A·sin(ωt+α32)IV2=−A·sin(ωt+α32+2π/3)IW2=−A·sin(ωt+α32−2π/3)IU3=−A·sin(ωt+α32)IV3=−A·sin(ωt+α32+2π/3)IW3=−A·sin(ωt+α32−2π/3)IU4=A·sin(ωt+α32)IV4=A·sin(ωt+α32+2π/3)IW4=A·sin(ωt+α32−2π/3)IU5=A·sin(ωt+α32)IV5=A·sin(ωt+α32+2π/3)IW5=A·sin(ωt+α32−2π/3)IU6=−A·sin(ωt+α32)IV6=−A·sin(ωt+α32+2π/3)IW6=−A·sin(ωt+α32−2π/3)IU7=−A·sin(ωt+α32)IV7=−A·sin(ωt+α32+2π/3)IW7=−A·sin(ωt+α32−2π/3)IU8=A·sin(ωt+α32)IV8=A·sin(ωt+α32+2π/3)IW8=A·sin(ωt+α32−2π/3)  [Equation 9]

For driving the rotary electric machine 10 in the 4-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 10, to flow through the respectivephase windings:IU1=A·sin(ωt/2+α33)IV1=A·sin(ωt/2+α33−2π/3)IW1=A·sin(ωt/2+α33+2π/3)IU2=−A·sin(ωt/2+α33)IV2=−A·sin(ωt/2+α33−2π/3)IW2=−A·sin(ωt/2+α33+2π/3)IU3=A·sin(ωt/2+α33)IV3=A·sin(ωt/2+α33−2π/3)IW3=A·sin(ωt/2+α33+2π/3)IU4=−A·sin(ωt/2+α33)IV4=−A·sin(ωt/2+α33−2π/3)IW4=−A·sin(ωt/2+α33+2π/3)IU5=−A·sin(ωt/2+α33)IV5=−A·sin(ωt/2+α33−2π/3)IW5=−A·sin(ωt/2+α33+2π/3)IU6=A·sin(ωt/2+α33)IV6=A·sin(ωt/2+α33−2π/3)IW6=A·sin(ωt/2+α33+2π/3)IU7=−A·sin(ωt/2+α33)IV7=−A·sin(ωt/2+α33−2π/3)IW7=−A·sin(ωt/2+α33+2π/3)IU8=A·sin(ωt/2+α33)IV8=A·sin(ωt/2+α33−2π/3)IW8=A·sin(ωt/2+α33+2π/3)  [Equation 10]

For driving the rotary electric machine 10 in the 2-pole mode, thecontroller 15 causes the following electrical currents, which areexpressed by the following equations 11, to flow through the respectivephase windings:IU1=A·sin(ωt/4+α34)IV1=A·sin(ωt/4+α34+2π/3)IW1=A·sin(ωt/4+α34−2π/3)IU2=−A·sin(ωt/4+α34)IV2=−A·sin(ωt/4+α34+2π/3)IW2=−A·sin(ωt/4+α34−2π/3)IU3=A·sin(ωt/4+α34)IV3=A·sin(ωt/4+α34+2π/3)IW3=A·sin(ωt/4+α34−2π/3)IU4=−A·sin(ωt/4+α34)IV4=−A·sin(ωt/4+α34+2π/3)IW4=−A·sin(ωt/4+α34−2π/3)IU5=A·sin(ωt/4+α34)IV5=A·sin(ωt/4+α34+2π/3)IW5=A·sin(ωt/4+α34−2π/3)IU6=−A·sin(ωt/4+α34)IV6=−A·sin(ωt/4+α34+2π/3)IW6=−A·sin(ωt/4+α34−2π/3)IU7=A·sin(ωt/4+α34)IV7=A·sin(ωt/4+α34+2π/3)IW7=A·sin(ωt/4+α34−2π/3)IU8=−A·sin(ωt/4+α34)IV8=−A·sin(ωt/4+α34+2π/3)IW8=−A·sin(ωt/4+α34−2π/3)  [Equation 11]

Here, a supplementary description of the energization control in eachpole number mode is provided. In the 16-pole mode, as can be understoodfrom Equation 8 above, the controller 15 causes the directions of theenergization currents of each group and each phase to all be identical.As a result, as shown in FIG. 30, the energization directions of the twogroups of phase windings in the same slot become identical in thesingle-group slots and all of the mixed-group slots, and the number ofpoles of the rotary electric machine 10 becomes a maximum value (16poles).

Furthermore, in the 8-pole mode, as can be understood from Equation 9above, the controller 15 reverses, among the energization currents ofeach group and each phase, the direction of the energization currents ofthe second group, the third group, the sixth group, and the seventhgroup (IU2, IV2, IW2, IU3, IV3, IW3, IU6, IV6, IW6, IU7, IV7, and IW7).In this case, for example, among the U1-U2, U2-U3, U3-U4, U4-U5, U5-U6,U6-U7, and U7-U8 combinations of phase windings in the U-phasemixed-group slots, the energization directions become identical for theU2-U3, U4-U5, and U6-U7 combinations, and the energization directionsare mutually opposing for all other combinations. As a result, as shownin FIG. 31, the energization directions of the two groups of phasewindings in the same slot become identical in the single-group slots andsome of the mixed-group slots (mixed-group slots which are combinationsof the second and third groups, the fourth and fifth groups, and thesixth and seventh groups), and the number of poles of the rotaryelectric machine 10 becomes 8 poles.

Furthermore, in the 4-pole mode, as can be understood from Equation 10above, the controller 15 reverses, among the energization currents ofeach group and each phase, the direction of the energization currents ofthe second group, the fourth group, the fifth group, and the seventhgroup (IU2, IV2, IW2, IU4, IV4, IW4, IU5, IV5, IW5, IU7, IV7, and IW7).In this case, for example, among the U1-U2, U2-U3, U3-U4, U4-U5, U5-U6,U6-U7, and U7-U8 combinations of phase windings in the U-phasemixed-group slots, the energization directions become identical for theU4-U5 combination, and the energization directions are mutually opposingfor all other combinations. As a result, as shown in FIG. 32, theenergization directions of the two groups of phase windings in the sameslot become identical in the single-group slots and some of themixed-group slots (mixed-group slots which are combinations of thefourth and fifth groups), and the number of poles of the rotary electricmachine 10 becomes 4 poles.

Furthermore, in the 2-pole mode, as can be understood from Equation 11above, the controller 15 reverses, among the energization currents ofeach group and each phase, the direction of the energization currents ofthe second group, the fourth group, the sixth group, and the eighthgroup (IU2, IV2, IW2, IU4, IV4, IW4, IU6, IV6, IW6, IU8, IV8, and IW8).In this case, for example, the energization directions are mutuallyopposing for the U1-U2, U2-U3, U3-U4, U4-U5, U5-U6, U6-U7, and U7-U8combinations of phase windings in the U-phase mixed-group slots. As aresult, as shown in FIG. 33, the energization directions of the twogroups of phase windings in the same slot become identical in only thesingle-group slots, and the number of poles of the rotary electricmachine 10 becomes 2 poles.

In other words, as shown in FIG. 30 to FIG. 33, the controller 15selectively executes, at the time of energization of the phase windings,a first task (see FIG. 31 and FIG. 32) which causes the energizationdirections of the phase windings in some of the mixed-group slots tobecome different, and a second task (see FIG. 33) which causes theenergization directions of the phase windings in all of the mixed-groupslots to become different.

According to the above configuration of the present embodiment, the twogroups of phase windings accommodated in the mixed-group slots representseven different types of combinations for each phase. In this case, byusing the mixed-group slots having seven types of combinations for eachphase, and appropriately energizing the mixed-group slots, anadvantageous configuration can be realized when implementing a polenumber ratio having multiple levels.

Modifications

The embodiments above may, for example, be modified as follows.

For example, in the configuration in FIG. 1, the stator windings 11 and12 (two groups of phase windings) are respectively configured to beconnected to the three-phase inverters 13 and 14, but this may bemodified. For example, as shown in FIG. 34, a configuration may beimplemented in which the stator windings 11 and 12 (two groups of phasewindings) are connected to a six-phase inverter 81.

In the embodiments described above, the groups of phase windings arearranged on the radially inner side and the radially outer side insidethe slots 34, but it is not limited to this, and a configuration may beimplemented in which the groups of phase windings are provided by beingarranged in the circumferential direction inside the slots 34.

In the rotary electric machine 10, the rotor 22 may be configured by arotor that uses a permanent magnet. FIG. 35 shows an example in whichthe inductor-type rotor in FIG. 4 has been replaced by a permanentmagnet-type rotor. In this case, the rotor 22 is configured by a rotorcore 91, and permanent magnets 92 provided on an outer circumferentialportion of the rotor core 91. In the rotor 22, fixed magnetic poles ofthe permanent magnets 92 and a magnetic pole of the rotor core 91 arearranged in the circumferential direction, and the number of poles ofthe rotor 22 is switched by reversing the polarity of the magnetic poleof the rotor core 91 in response to a stator magnetomotive force. As aresult of using the permanent magnets 92, because the rotor magneticpole can be configured without an electromagnet that includes asecondary conductor, loss reduction is achieved with respect to therotor 22, and the efficiency of the rotary electric machine 10 can beincreased. Furthermore, the cooling function can be simplified, and thephysical size can be made smaller.

The present disclosure has been described based on the embodiments,however, it is to be understood that the present disclosure is notlimited to these embodiments and constructions. The present disclosurealso includes various modifications and equivalent variations. Inaddition, the various combinations and configurations, and othercombinations and configurations including more, less, or only a singleelement, are also within the scope and spirit of the present disclosure.

What is claimed is:
 1. A rotary electric machine comprising: a rotor;and a stator comprising: stator windings including n groups ofthree-phase windings, where n is a power of 2; and a plurality of slotswith the stator windings wound therein, the slots being provided in acircumferential direction of the stator and including: first slots thateach only accommodate portions of same-group and same-phase windings inthe n groups of three-phase windings, energizing directions of thesame-group and same-phase windings being identical to each other; andsecond slots each accommodating different-group and same-phase windingsin the n groups of three-phase windings; wherein the first slots and thesecond slots are arranged in the stator at predetermined intervals in acircumferential direction of the stator, the three-phase windings ofeach group are wound around the stator with regular intervalstherebetween, and a number of poles of the rotary electric machine isconfigured to be changeable.
 2. The rotary electric machine according toclaim 1, wherein: the first slots respectively for different groups inthe n groups are arranged at intervals of m slots in the circumferentialdirection of the stator; and (m−1) second slots are each arrangedbetween a corresponding pair of the first slots of the different groups.3. The rotary electric machine according to claim 1, wherein: each ofthe second slots accommodates a same number of the different-group andsame-phase windings for each of the different groups.
 4. The rotaryelectric machine according to claim 1, wherein the stator windingsinclude 2{circumflex over ( )}(A−1) groups of phase windings as the ngroups of phase windings; the second slots include slots, each of theslots accommodating a unique combination of two groups of phase windingsselected from the 2{circumflex over ( )}(A−1) groups of phase windings;and the number of poles of the rotary electric machine is configured tobe changeable in the A steps.
 5. The rotary electric machine accordingto claim 1, wherein: the n groups of phase windings are comprised of afirst group to an nth group of phase windings; and the second slotsinclude slots that accommodate, for each phase, (n−1) types ofcombinations of any two-different group windings selected from the firstgroup to the nth group.
 6. A rotary electric machine system comprising:the rotary electric machine according to claim 1; and a computerconfigured to control energization of each of the phase windings in therotary electric machine, the computer being configured to: performenergization of each of the different-phase and same-group windingsaccommodated in a corresponding one of the second slots such thatenergization directions of the respective different-phase and same-groupwindings are identical to each other; perform energization of each ofthe different-phase and same-group windings accommodated in acorresponding one of the second slots such that energization directionsof the respective different-phase and same-group windings are differentfrom each other; and switch between energization of each of thedifferent-phase and same-group windings in identical energizationdirections, and energization of the each of the different-phase andsame-group windings in different energization directions.
 7. The rotaryelectric machine system according to claim 6, wherein: the second slotsin the rotary electric machine include slots, each of the slotsaccommodating a unique combination of two groups of phase windingsselected from the n groups of phase windings; and the computer isconfigured to selectively perform: a first operation that causesenergization directions of the phase windings disposed in at least oneof the second slots among all of the second slots to be different fromeach other; and a second task that causes energization directions of thephase windings in all of the second slots to be different from eachother.
 8. The rotary electric machine system according to claim 6,wherein the computer is configured to: perform control of theenergization of each of the different-phase and same-group windingsaccommodated in a corresponding one of the second slots using apredetermined first number X1 of poles of the rotary electric machine;and when performing control of the energization of each of thedifferent-phase and same-group windings accommodated in a correspondingone of the second slots using a predetermined second number X2 of polesof the rotary electric machine, set an energization frequency for eachof the different-phase and same-group windings to a value of 1/B, thesecond number X2 being expressed by the following equation:X2=X1/B
 9. The rotary electric machine system according to claim 6,further comprising: power converters provided for the respective ngroups of phase windings, wherein the computer is configured to causeeach of the power converters to perform power conversion to accordinglycontrol energization of each of the stator windings included in acorresponding one of the second slots.